This proposal is designed to define the role of the renal sympathetic nerves in the direct control of tubular sodium reabsorption in the normal animal. Previous work in sodium-retaining states has shown that, with other variables known to alter tubular sodium transport constant, interruption of renal sympathetic nerve traffic results in a natriuresis. Further support for a direct role of the renal sympathetic nerves in regulating tubular sodium reabsorption is the anatomic evidence which shows adrenergic nerve terminals in direct contact with the basement membranes of proximal and distal tubular epithelial cells in mammalian renal cortex. Using techniques of direct and reflex renal sympathetic nerve stimulation, we propose to delineate a role for the neural control of tubular sodium reabsorption in the normal animal.